PT  - JOURNAL ARTICLE
AU  - T. S. Cohen
AU  - K. J. Cavanaugh
AU  - S. S. Margulies
TI  - Frequency and peak stretch magnitude affect alveolar epithelial permeability
AID  - 10.1183/09031936.00141007
DP  - 2008 Oct 01
TA  - European Respiratory Journal
PG  - 854--861
VI  - 32
IP  - 4
4099  - http://erj.ersjournals.com/content/32/4/854.short
4100  - http://erj.ersjournals.com/content/32/4/854.full
SO  - Eur Respir J2008 Oct 01; 32
AB  - The present study measured stretch-induced changes in transepithelial permeability to uncharged tracers (1.5–5.5 Å) using cultured monolayers of alveolar epithelial type-I like cells. Cultured alveolar epithelial cells were subjected to uniform cyclic (0, 0.25 and 1.0 Hz) biaxial stretch from 0% to 12, 25 or 37% change in surface area (ΔSA) for 1 h. Significant changes in permeability of cell monolayers were observed when stretched from 0% to 37% ΔSA at all frequencies, and from 0% to 25% ΔSA only at high frequency (1 Hz), but not at all when stretched from 0% to 12% ΔSA compared with unstretched controls. At stretch oscillation amplitudes of 25 and 37% ΔSA, imposed at 1 Hz, tracer permeability increased compared with that at 0.25 Hz. Cells subjected to a single stretch cycle at 37% ΔSA (0.25 Hz), to simulate a deep sigh, were not distinguishable from unstretched controls. Reducing stretch oscillation amplitude while maintaining a peak stretch of 37% ΔSA (0.25 Hz) via the application of a simulated post-end-expiratory pressure did not protect barrier properties. In conclusion, peak stretch magnitude and stretch frequency were the primary determining factors for epithelial barrier dysfunction, as opposed to oscillation amplitude.